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As the structure of power grid becomes more and more complex, the previous lightning overvoltage statistical waveform is no longer suitable for the current power system. So the lightning overvoltage need to be measured to restatistic. In this paper, the measuring system based on Pockels effects and a method of waveform processing are proposed to analyze the time parameters of induced overvoltage, including filtering by wavelet transform and identifying induced overvoltage by the degree of similarity between the three-phase waveforms. Furthermore, the front time, the time to half value and the power frequency phase angles corresponding to the moment of induced overvoltage are statistically analyzed to conclude the value with the maximum probability as well as the randomness of the moment of induced overvoltage, which can guide the insulation design and test of power equipment.

The lightning-induced overvoltage is the main reason for the failure of the low voltage (LV) distribution lines. In order to simulate of lightning-induced overvoltage, this paper calculates the space electromagnetic field generated by the lightning based on the existing channel-base current and lightning return stroke current models; then using the Agrawal field-to-line coupling model the overvoltage caused by lightning strikes near the distribution line is calculated by the finite difference-time domain (FDTD) method. The influence of ground loss is considered by the method of Cooray-Rubinstein formula and vector fitting. The correctness of the algorithm is verified by the literature result. Based on this algorithm, the characteristics of the induced overvoltage on the transmission line and the influence of the insulator, the lightning current waveform, the position of the lightning strike point and the ground conductivity, to the induced overvoltage is analyzed.